Back in 2005, grad students at Carnegie Mellon University created over fifty games in the course a semester. While none of them had the polish that a A-list title would have, they all managed to "find the fun" and the games were immensely entertaining. With a little more work and polish, they might have made wonderful iPhone or other mobile applications and, with a distributor, might have made a good in-store boxed game.
For indie developers who think about the budgets to create God of War or a Dungeons and Dragons Online, the task of creating a fun game might seem impossible. Sure, iShoot was popular when the App Store was young and unsaturated, but the bar's been raised and there's far more competition there. There are few places other than Facebook and MySpace where a good, fun, but unpolished game have a chance to succeed these days.
Finding the fun is the main element for a successful game, regardless of the venue. The indie developer needs to focus on the essence of the game. Too many games are ruined by attempts to add complexity to the game that just muddy the playability and make it tedious. For instance, FarmVille on Facebook is essentially a resource management game with a little sandbox nature to it - what to plant, when to plant, and how long before you can harvest. But with the holidays they added tons of other features, including a lot of superfluous items (candy cane benches?). For people who liked the sandbox aspect of the game, this was a boon. For people who liked the resource management piece of it, this bogged down playability, added nothing in terms of "fun", and pushed people away (including myself, mostly).
What the CMU project proved is that indie developers can create, in small groups or even just by themselves if they choose, fun-filled games that people can enjoy without spending millions of dollars or having a huge content team. Do games with large staffs tend to do better? On the whole, yes, but for every World of Warcraft there are a dozen Tetrises that have niche followings. When something like that breaks it big, it can redefine a genre. Or create a new one. And who does that best? Indie developers.
Code on, indie developers, and change the world.